Positive control engine starter

ABSTRACT

A positive control engine starter with a novel coupling between the drive pinion and a helical-spline drive shaft, the coupling including male and female coupling elements cooperating with one another over an axial clearance and an angular clearance. The coupling parts are axially and angularly spring-biased against closing of the clearance gaps, thereby allowing the pinion to yield axially and angularly when tooth collision occurs during engagement. The same spring bias facilitates the pinion retraction after engine firing, by temporarily eliminating the tooth pressure on the gears and by initiating the retracting motion of the male coupling part on the drive shaft.

United States Patent [191 Molliet Feb. 12, 1974 POSITIVE CONTROL ENGINESTARTER [76] Inventor: Jules Henri Molliet, 2, rue

Traversiere, 21 Amay-le-Duc, France [22] Filed: Dec. 10, 1971 [21] Appl.No.: 206,706

[30] Foreign Application Priority Data Dec. 15, 1970 France 7045926 [52]US. Cl. 74/7 R, 64/14 [51] Int. Cl. F02n 15/06 [58] Field of Search 74/7A, 7 R; 64/14, 15 C [56] References Cited UNITED STATES PATENTS2,569,267 9/1951 Tobias 74/7 3,410,111 11/1968 Ireland 64/14 1,022,999.4/1912 Bashaw 64/14 2,944,428 7/1960 Antonidis et a1. 74/7 Digby 74/ 7X FOREIGN PATENTS OR APPLICATIONS 68,387 3/1914 Switzerland 64/14Primary ExaminerBenjamin W. Wyche Attorney, Agent, or Firm-Otto JohnMunz [57] ABSTRACT A positive control engine starter with a novelcoupling between the drive pinion and a helical-spline drive shaft, thecoupling including male and female coupling elements cooperating withone another over an axial clearance and an angular clearance. Thecoupling parts are axially and angularly spring-biased against closingof the clearance gaps, thereby allowing the pinion to yield axially andangularly when tooth collision occurs during engagement. The same springbias facilitates the pinion retraction after engine firing, bytemporarily eliminating the tooth pressure on the gears and byinitiating the retracting motion of the male coupling part on the driveshaft.

7 Claims, 6 Drawing Figures PATENTED FEB 12 I974 I nvenlor JULES HENRIMOLLI ET y A Home 1 POSITIVE CONTROL ENGINE STARTER BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention relates tostarter devices,of the so-called positive control type, for internalcombustion engines. Y

2. Description of the Prior Art It is known that starter devices areessentially of two types, i.e. the inertia type and the positive controltype. In inertia type devices a pinion is internally threaded and issupported on a threaded drive shaft of the starter motor. When thestarter begins to rotate, the internal combustion engine being atstandstill, the rotational inertia of the pinion causes it to advance onthe threaded drive shaft until the pinion engages a ring gear, usuallyintegral with the flywheel of the engine, after which the starter cranksthe internal combustion engine for startup. As soon as; when the latterfires, the starter pinion becomes a driven member instead of a drivingmember and the pinion moves back on its threaded driving shaft to itsrest position, in which it is held by a spring.

Inertiatype starter devices suffer from certain drawbacks and are beingreplaced to an ever-increasing extent by starters of the so-calledpositive control type. The main disadvantages of inertia type starterdevices is the fact that during the operation of the starter a tooth ofthe starter pinion may come to abut against a tooth of the ring gearwheel when the longitudinal movement of the starter device takes place,causing the pinion to be blocked against engagement.

' A starter device of the positive control type is moved towards thering gear by means of fork, which causes the teeth of the pinion toengage those of the ring gear at the moment when the starting actiontakes place, just before-the motor of the starter is set in operation.After the internal combustion engine is started up, the fork moves thestarter device back again, assisted bythe fact that it is the ring gearwheel that drives while the pinion is driven.

To cause a starter device to advance onthe shaft of the starter by meansof a fork exerting a longitudinal force, the screw pitch of the pinionand'of its driving shaft must be greater than that of inertia typestarter device the driving shaft therefore being helically splinedratherthan threaded. In this case, however, the fork action is required toretract the starter device when the engine is started up, just as it wasnecessary to cause the pinion to engage the ring gear at the beginningof the starting-up operation. Furthermore, in the event of excessivespeed of rotation of the engine just after being started up there is arisk of the starter motor likewise being driven at an excessive speed,resulting in its possible damage. In fact, if the excessive speed isconsiderable the starter device is subjected to a high torque whichlocks it against axial movement on the driving shaft and therebymaintains the pinion in engagement the ring gear, the fork being therebyprevented from retracting it to its position of rest.

For these reasons starter devices of the positive control type havebeen'fitted with a free wheel device which separates the pinionangularly and at least partially from the body of the starter'device sothat the motor of the starter cannot be driven at excessive speed andthe starter-device cannot be locked on the spline shaft.

Various free wheel systems have been suggested, and although some ofthem function satisfactorily they are comparativaly complex andexpensive devices.

SUMMARY OF THE INVENTION An object of this invention is to replace thepreviously required free wheel systems of positive control type starteddevices by a simpler and thus less expensive coupling which despite itssimplicity will prove equally reliable.

According to the present invention a starter device of the positivecontrol type includes a drive pinion, an internally splined socketmounted on a helically splined drive shaft and a novel coupling betweenthe pinion and the socket, said coupling comprising two parts fittinginto one another with clearances between the two parts which allowlimited longitudinal and rotational movements between them and dampingmeans biasing the two coupling parts against closing of clearances.

The principle on which the invention is based is as follows to enablethe starter device to be retracted to its rest position by means of afork after the internal combustion engine has been started up and toovercome the friction even if the driving torque exerted by the saidengine is extremely high, the socket of the device must be rotationallyseparated at least momentarily, from the pinion. The free wheelcoupling, one part of which separates from the other angularly, but notlongitudinally, is a means of doing this. If the pinion can rotatefreely over a certain angle only, and if this limited angular clearanceis combined with a longitudinal clearance, suitable damping means beingprovided for each of the clearances, this may suffice to relieve thetooth pressure by which the ring gear retains the pinion and to enablethe fork to move back the starter device, as in the case of a free wheelcoupling. In other words, the limited angular clearance combines withthe longitudinal clearance to momentarily free the gear teeth.

The unexpected fact is that it is not necessary for these clearances tobe particularly large to enable a coupling according to the invention tofunction correctly; experience has shown that even with fairly limitedclearances, of the order of a millimeter in the longitudinal direction,and of a few degrees in the direction of rotation (e.g. 3), the returnmovement of the pinion is effected under satisfactory conditions,without any risk of the started engine driving the starter at excessivespeed. This has been demonstrated by numerous starting-up tests carriedout by the inventor. This unexpected result, constitutes a majoradvantage of the invention because these limited clearances makepossible a very compact arrangement, a far less complex and thereforeless expensive machining and finishing process than in the case with thefree wheel connection hitherto used in connection with positive controlstarter devices. These clearances must nevertheless be appropriatelyspring-biased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a coupling for a starterdevice of the positive control type in accordance with the invention andcomprising a male and a female part,

FIG. 2 is a partial section through the male and female parts of FIG. 1'with the male and female parts in a slightly different position,

FIG. 3 is an end view of the female part, FIG. 4 is a plan view of thefemale part, FIG. 5 is an end view of the male part, and FIG. 6 is aplan view of the male part.

DESCRIPTION OF THE PREFERRED EMBODIMENT These figures as a whole show acoupling according to the invention, intended to connect a pinion 2 of astarter device of the positive control type with an internally flutedsocket 3, normally mounted on the helical spline shaft 4 of a sTartermotor (not shown). This coupling comprises a pinion 2, integral with afemale part whose general form is that of a cylinder notched at the endopposite the pinion to provide a rectangular recess 21, thus forming apair of jaws 27 and 28, and bored out to form a cylindrical opening 22(FIG.3). The said female part also includes a circular recess 29(FIG.2), of the same diameter as the socket 3, and two blind bores 23and 24, located symmetrical with resepect of the axis of the pinion 2and of the female part 20. Finally, the jaws 27 and 28 of the femalepart are provided on their outer periphery with circular grooves and 26,which can be seen more clearly in FIGS. 3 and 4 lntegrally with thesocket 3, there is provided a male part 30 taking the general form of aletter T and of such dimensions as to enable it to be introduced, with acertain clearance, into the rectangular recess 21 of the female. Thebranches 31 and 32 of the T terminate in a part rounded portion 33 ofthe same diameter radius as the female part 20 and are provided on theouter surface with circular grooves 34 and 35, somewhat larger in theaxial direction than the grooves 25 and 26 of the female part. Finally,each of the branches 31 and 32 has a cylindrical blind bore 36 and 37respectively, symmetrical with respect to the axis of the socket 3 butasymmetrical in respect of the general planes of symmetry of the malepart 30 Spring-mounted pushers 41, 42, 43, 44 are adapted to beaccomodated in the bores 23, 24, 36, 37 and a retaining ring 126 ofspring steel, of the same diameter as the circular grooves 25 and 26snaps into the latter.

When a coupling of this type is assembled (FIGS. 1 and 2), the femaleand male parts 20 and 30 respectively fit into each other, thespring-mounted pushers 41 44 occupy their respective bores, and thespring ring 126 fits into the grooves 25, 26 34, to connect the twoparts together. The end 38 of the socket 3 (FIG. 6) is accomodated inthe recess 29 (FIG. 2) of the female part, resulting in highlysatisfactory centering. It does not, however, abut the base of therecess (FIG. 1), but is biased back by the spring-mounted pushers 41 and42, acting on the branches 31 and 32 of the male part. A longitudinalclearance 51 thus exists between the branches 31 and 32 and the base ofthe jaws 27 and 28, as well as a clearance 52 to the right of the springring 126 in the grooves 34 and 35 of the branches 31 and 32, thesegrooves being, as already stated, larger than the corresponding grooves25 and 26 of the female part 20.

Furthermore, the pushers 43 and 44, acting in the same direction ofrotation of the branches with respect to the jaws, result in arotational clearance 53 between the branches and the jaws, on the sidevisible in FIG. 1.

The starter device thus assembled forms an articulated assembly, havingboth a-longitudinal and a rotational clearance, compensated by the twolongitudinal dampers and the two transversal dampers which constitutethe pushers 41, 42, 43 and 44. The thrust of the longitudinal dampers islimited by the spring ring 126. The centering of the two parts issatisfactorily ensured by the bearing engagement between the extremity38 of the socket 3 in the recess 29.

A starter device fitted with a coupling according to the inventionoperates as follows 1 At the moment of starting, a fork (not shown),controlled by a solenoid or by a manual pull device, acts on a collarshown in broken lines at 54, shifting the device as a whole towards theleft, in the manner already known per se. The pinion 2 approaches thering gear (not shown) and engages it. At the end of the travel thepinion 2 comes to abut against a stop 40 at the end of the spline shaft4 the pushers 41 and 42 undergo compression and the clearance 51 istaken up (position shown in FIG. 2). If, at the moment when the pinionis about to mesh with the ring gear a tooth of the former comes to abutagainst a tooth of the latter, the socket 3 is able to continue itsaxial movement, compressing the still extended pushers 41 and 42(position shown in FIG. 2) the socket thereby rotates to a small angleagainst the bias of radial (pushers 43 and 44 sufficiently to overcomethe abutment between the aforementioned teeth. The pinion then mesheswith the ring gear and at the end of its travel, abutting against thestop 40, the clearance 51 is taken up as already described. The motor ofthe starter is now set in operation, cranking the internal combustionengine, the pushers 43 and 44 being compressed, and the clearance 53taken up.

At the completion of when the engine rotates of its own power, thestarting operation, the ring gear tends to move more rapidly than thepinion, and the four pushers expand simultaneously, nullifying the toothpressure exerted by the ring gear (which has become a driving gear) onthe pinion during a period which, although extremely short, issufficient to enable the fork to retract the starter device to the righttoward its position of rest. After this retraction has commenced thereis no reason why this movement should not continue, since, due to thehelix of the spline shaft, the greater the speed gathered by the devicein its movement towards the right, the greater the extent to which thestress tooth pressure exerted by the ring gear on the pinion will berelieved: the retracting movement of the starter device thus continues.

I claim:

1. In a positive control engine starter where the drive pinion isadvanced and retracted on the starter drive shaft by means of anindependent control element such as a solenoid-operated shifting fork orthe like, a coupling assembly between the pinion and the drive shaftcomprising in combination:

a first coupling member connected to the rear of the drive pinion, thepinion and first coupling member being guided on the drive shaft forrotation and axial displacement relative thereto between a forwardengagement position and a retracted rest position;

a second coupling member arranged axially behind the first couplingmember and including a rotational connection with the drve shaftallowing of axial displacement thereon along a helix whose axialreaction force under cranking torque is directed toward the drivepinion;

means for angularly connecting the first and second coupling members insuch a way that the two members engage one another rotationally in bothdirections, with an angular clearance permitting a limited angulardisplacement between the coupling members;

means for angularly biasing the coupling members against each other inthe direction in which the pinion and first coupling member areangularly retarded relative to the second coupling member in therotational sense of cranking; and

means for axially biasing the drive pinion away from the second couplingmember independently from the angular biasing means so as to allow arelative approaching motion therebetween, when the pinion encounters anobstacle during its forwardmo tion into gear engagement;

the drive pinion and the first coupling member are solidary with oneanother, and the axial biasing means are arranged between the first andsecond coupling members;

the coupling assembly further comprising:

means for axially connecting the first and second coupling members insuch a way that the two members engage one another axially in bothdirections, with an axial clearance permitting a limited axialdisplacement between the coupling members.

2. A coupling assembly as defined in'claim 1, wherein the axial biasingmeans and the angular biasing means include compression springs betweeenthe first and second coupling members.

3. A coupling assembly as defined in claim 1, wherein the male andfemale coupling members form a substantially cylindrical commonperiphery in the area of axial engagement, the circumference of saidcy-' lindrical periphery being formed in part by nonrecessed portions ofthe female coupling member and in part by the axial protrusions of themale coupling member; and

the axial connecting means between the coupling members includes acircumferential groove traversing both the male and female portionswithin the common cylindrical periphery, and a retainer ring receivedwithin said circumferential groove which engages the groove portions ofboth coupling members with the indicated axial clearance.

5. A coupling assembly as defined in claim 4, wherein thecircumferential groove of the axial connecting means has a groove widthin the circumferential portions of the female coupling substantially ofthe same dimension as the retainer ring, and a groove width in thecircumferential portions of the male coupling which is axially larger byat least the amount of the indicated axial clearance.

6. A coupling assembly as defined in Claim 4,

wherein the first coupling member is the female member, having asubstantially cylindrical outer periphery, an enlarged recessed centerbore in its rear portion, and a transverse slot therethrough forming twooppositely located rectangular axial recesses in the rear portion of thecoupling member; and

the second coupling member is the male member,

having a cylindrical trunnion adapted to be received and centered in thecenter bore of the female member, and a pair of parallel-faced lobesadapted to be received in the two axial recesses of the female memberwith the indicated angular clearance, the radial ends of the lobeshaving a radius corresponding to that of the cylindrical periphery ofthe female coupling member.

7. A coupling assembly as defined in claim 6, wherein the axial biasingmeans includes axially oriented compression springs arranged in thebottom of the axial recesses of the female coupling members so I as tobias the cooperating axial protrusions of the male coupling member outof these recesses; and the rotational biasing means includescircumferentially oriented compression springs arranged between opposingradially oriented surface portions of the axial recesses in the femalecoupling member on the one hand and the cooperating axial protrusions ofthe male coupling member on the other hand.

1. In a positive control engine starter where the drive pinion isadvanced and retracted on the starter drive shaft by means of anindependent control element such as a solenoid-operated shifting fork orthe like, a coupling assembly between the pinion and the drive shaftcomprising in combination: a first coupling member connected to the rearof the drive pinion, the pinion and first coupling member being guidedon the drive shaft for rotation and axial displacement relative theretobetween a forward engagement position and a retracted rest position; asecond coupling member arranged axially behind the first coupling memberand including a rotational connection with the drve shaft allowing ofaxial displacement thereon along a helix whose axial reaction forceunder cranking torque is directed toward the drive pinion; means forangularly connecting the first and second coupling members in such a waythat the two members engage one another rotationally in both directions,with an angular clearance permitting a limited angular displacementbetween the coupling members; means for angularly biasing the couplingmembers against each other in the direction in which the pinion andfirst coupling member are angularly retarded relative to the secondcoupling member in the rotational sense of cranking; and means foraxially biasing the drive pinion away from the second coupling memberindependently from the angular biasing means so as to allow a relativeapproaching motion therebetween, when the pinion encounters an obstacleduring its forward motion into gear engagement; the drive pinion and thefirst coupling member are solidary with one another, and the axialbiasing means are arranged between the first and second couplingmembers; the coupling assembly further comprising: means for axiallyconnecting the first and second coupling members in such a way that thetwo members engage one another axially in both directions, with an axialclearance permitting a limited axial displacement between the couplingmembers.
 2. A coupling assembly as defined in claim 1, wherein the axialbiasing means and the angular biasing means include compression springsbetweeen the first and second coupling members.
 3. A coupling assemblyas defined in claim 1, wherein the first and second coupling members arein the form of male and female cooperating parts; the angular connectingmeans between the coupling members including one or several off-centeraxial recesses in the female coupling member and matching axialprotrusions in the male coupling member engaging the female recesseswith the indicated angular clearance.
 4. A coupling assembly as definedin claim 3, wherein the male and female coupling members form asubstantially cylindrical common periphery in the area of axialengagement, the circumference of said cylindrical periphery being formedin part by non-recessed portions of the female coupling member and inpart by the axial protrusions of the male coupling member; and the axialconnecting means between the coupling members includes a circumferentialgroove traversing both the male and female portions within the commoncylindrical periphery, and a retainer ring received within saidcircumferential groove which engages the groove portions of bothcoupling members with the indicated axial clearance.
 5. A couplingassembly as defined in claim 4, wherein the circumferential groove ofthe axial connecting means has a groove width in the circumferentialportions of the female coupling substantially of the same dimension asthe retainer ring, and a groove width in the circumferential portions ofthe male coupling which is axially larger by at least the amount of theindicated axial clearance.
 6. A coupling assembly as defined in Claim 4,wherein the first coupling member is the female member, having asubstantially cylindrical outer periphery, an enlarged recessed centerbore in its rear portion, and a transverse slot therethrough forming twooppositely located rectangular axial recesses in the rear portion of thecoupling member; and the second coupling member is the male member,having a cylindrical trunnion adapted to be received and centered in thecenter bore of the female member, and a pair of parallel-faced lobesadapted to be received in the two axial recesses of the female memberwith the indicated angular clearance, the radial ends of the lobeshaving a radius corresponding to that of the cylindrical periphery ofthe female coupling member.
 7. A coupling assembly as defined in claim6, wherein the axial biasing means includes axially oriented compressionsprings arranged in the bottom of the axial recesses of the femalecoupling members so as to bias the cooperating axial protrusions of themale coupling member out of these recesses; and the rotational biasingmeans includes circumferentially oriented compression springs arrangedbetween opposing radially oriented surface portions of the axialrecesses in the female coupling member on the one hand and thecooperating axial protrusions of the male coupling member on the otherhand.